解方程[P(n,5)+P(n,4)]/P(n,3)=4_数学解答

解方程[P(n,5)+P(n,4)]/P(n,3)=4

人气：491 ℃　时间：2020-10-02 01:43:14

解答

[P(n,5)+P(n,4)]/P(n,3)=4
P(n,5)/P(n,3)+P(n,4)/P(n,3)=4
(n-3)(n-4)+(n-3)=4
(n-3)[n-4+1]=4
(n-3)^2=4
n-3=2
n=5.